<?php
//和其他类型的数据进行计算
echo 12+3.5,"\n";
echo 1200+"12abc","\n";//数字开头，转换12
echo 1200+"3e4yy","\n";//3乘以10的4次方，转换为30000
//echo 1200+"abc12","\n";abc12不数字开头，错误
//echo 1200+"","/n";不以数字开头，错误
echo 1200+true,"\n";//true转换为整数1
echo false+1200,"\n";//false转换成整数0
echo null+1200,"\n";//null转换为整数0
